NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.

Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.

U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

PUBLICATIONS

Ultrafast THz photoconductivity of photovoltaic polymer-fullerene blends: a comparative study correlated with photovoltaic device performance

Published

Author(s)

Edwin J. Heilweil, Jin Zuanming, Dominik Gehrig, Clare Dyer-Smith, Frederic Laquai, Mischa Bonn, Dmitry Turchinovich

Abstract

Ultrafast photo-induced carrier dynamics in prototypical low band-gap polymer:fullerene photovoltaic blend films PTB7:PC70BM and P3HT:PC70BM is investigated using ultrafast terahertz (THz) spectroscopy. The sub-picosecond (ps) and few-ps decays of THz-probed photoconductivities for both compounds are observed, attributed to the rapid formation of polaron pairs by exciton-exciton annihilation and subsequent polaron pair annihilation, respectively. The transient THz photoconductivity spectra of PTB7:PC70BM are well described by the Drude-Smith (DS) model, directly yielding the important charge transport parameters such as charge carrier density, momentum scattering time, and effective localization. By comparison with P3HT:PC70BM, we find that in PTB7:PC70BM the mobile charge carrier photoconductivity is significantly enhanced by a factor of 1.8 and prevails for longer times after charge formation, due to both improved mobile charge carrier yield and lower charge localization. In PTB7:PC70BM a strong dependency of electron momentum scattering time on electron density was found, well parameterized by empirical Caughey-Thomas model. The difference in ultrafast photoconductivities of both P3HT:PC70BM and PTB7:PC70BM is found to correlate very well with the performance of photovoltaic devices based on those materials.
Citation
Journal of Physical Chemistry Letters
Volume
5
Pub Type
Journals

Keywords

Terahertz spectroscopy, charge transfer, semiconducting polymers, organic photovoltaics, photoconductivity
Organic electronics, Semiconductors and Alternative energy

Citation

Heilweil, E. , Zuanming, J. , Gehrig, D. , Dyer-Smith, C. , Laquai, F. , Bonn, M. and Turchinovich, D. (2014), Ultrafast THz photoconductivity of photovoltaic polymer-fullerene blends: a comparative study correlated with photovoltaic device performance, Journal of Physical Chemistry Letters (Accessed October 13, 2025)

Issues

If you have any questions about this publication or are having problems accessing it, please contact [email protected].

Created October 10, 2014, Updated February 19, 2017
Was this page helpful?